Fe-Zn-S system and the sphalerite geobarometer
Fe-Zn-S system and the sphalerite geobarometer
Fe-Zn-S system and the sphalerite geobarometer
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D/O 18 - Geo<strong>the</strong>rmal Fluids Oxygen Isotope Thermometry<br />
<strong>Fe</strong>-<strong>Zn</strong>-S <strong>system</strong> <strong>and</strong> <strong>the</strong><br />
<strong>sphalerite</strong> <strong>geobarometer</strong>!<br />
� Iron content of <strong>sphalerite</strong> depends on aS 2 <strong>and</strong><br />
pressure!<br />
� Phase equilibria studies have revealed that <strong>the</strong> iron content of<br />
<strong>sphalerite</strong> equilibrated with pyrite <strong>and</strong> pyrrhotite, although<br />
temperature independent between about 300° <strong>and</strong> 550°C, is<br />
pressure dependent. !<br />
� This relationship has been defined (Scott <strong>and</strong> Barnes, 1971;<br />
Scott 1973) <strong>and</strong> thus allows <strong>the</strong> <strong>sphalerite</strong> composition in this<br />
assemblage to serve as a <strong>geobarometer</strong>. The equation below<br />
relates iron content (as <strong>Fe</strong>S) to <strong>the</strong> pressure of equilibration<br />
(Hutchison <strong>and</strong> Scott 1980): !<br />
� P bar =42.30-32.10 log mole% <strong>Fe</strong>S. !<br />
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